Electrical connectors are commonly used in the electronics industry in order to facilitate the interconnection of various components, usually by a plurality of conductive wires. Such connectors are typically formed as a row of a specified number of positions, with each position containing one or more connection sites. For example, a twelve position dual in-line connector will have twelve positions of two pins each, for a total of 24 pins or connection sites.
Electrical connectors may generally be divided into two classes: through-hole connectors and surface mount connectors. Through-hole connectors include conductive pins which protrude from their bottom surfaces and extend through holes formed in the printed circuit board to which the through-hole connector is mounted. Each of these pins is soldered to a conductive trace on the opposite side of the printed circuit board from the connector body. For example, if a through-hole connector has 24 pins, 24 holes will be formed in the printed circuit board with the same dimensional spacing between the through-holes as between the connector pins.
When a through-hole connector is mounted onto a printed circuit board, each of the connector pins extends through a respective through-hole in the printed circuit board. There can therefore be no misalignment between the mounted connector and the printed circuit board, because the through-holes positively locate the connector mounting position.
Surface mount connectors, on the other hand, do not mount to the printed circuit board using through-holes. A typical surface mount connector includes a conductive lead for each position protruding from the bottom surface of the connector. Each of these leads is formed in a curved configuration, such that the lead rests on a conductive pad on the surface of the printed circuit board, rather than extending through a through-hole in the board. The surface mount leads are soldered to these conductive pads.
Because no part of the surface mount connector extends through the printed circuit board, it is relatively easy to misalign the connector with respect to the pads when mounting the connector to the board. This is due to the fact that there are no through-holes or connector pins to positively locate the surface mount connector with respect to the printed circuit board surface.
In order to prevent such misalignment, prior art surface mount connectors have been constructed with alignment pins integrally formed with the connector body and protruding perpendicular to the bottom surface of the connector. Corresponding alignment holes are then formed in the printed circuit board, so that interaction between the alignment pins and the alignment holes will positively locate the surface mount connector on the surface of the printed circuit board. Such connectors are typically formed with one alignment pin near each end of the connector.
Surface mount connectors with alignment pins work well in locating the connector on the printed circuit board, however they are an inconvenience to connector manufacturers. This is because surface mount connectors without alignment pins may be inventoried by the connector manufacturer in only long strips of, for example, 50 positions. When a customer order is received, these long strips may be "cut to position" in order to form a connector of the desired number of positions. This obviates the need for the manufacturer to carry connectors with various numbers of positions in inventory, thus reducing inventory carrying costs.
This scheme will not work, however, if the connector must include an alignment pin on each end. Because the long strips must be able to be cut to any number of positions, it is not possible to know in advance where to locate the alignment pins. This necessitates the custom molding of such connectors in various sizes (i.e. various numbers of positions) with alignment pins near each end. A supply of each connector size must then be carried in inventory, greatly increasing the inventory carrying costs over such costs for connectors without alignment pins.
There is therefore a need in the prior art for a surface mount connector design which includes alignment pins, but which allows for the connectors to be inventoried in long strips and then cut to position as orders are received. The present invention is directed toward meeting this need.